How to extract a List element in the input mapping?

[Philipp_Ossler]

Hi @ajeans,

first, welcome to the Zeebe community

Thank you for raising this up!

@ajeans

But I only get two instances stuck at the boundary of the call activity, no incident, nothing…

Looking at the Zeebe logs, I get some pretty deep and internal stacktraces

It seems to be a bug in the implementation. Please create a new issue.

Regarding your questions:

@ajeans

Is my FEEL expression incorrect? Is there a better way to define it?

There is a small issue in the expression. In FEEL, the index of the list starts with 1 instead of 0, as you may expect from other languages. So, the expression to access the first element should be:

=applicants[1].token

@ajeans

Even with an incorrect FEEL expression, why does this not trigger an incident?

Usually, the deployment would be rejected or an incident would be created. But the bug broke the normal processing.

@ajeans

Simply with a parallel multi-instance call activity, inputCollection set as applicants and inputElement as applicant .
I had to change slightly the sub BPMN to look for applicant.token rather than token (I didn’t see a way to project part of the inputElement into a variable) but that is no big deal.

You can use the following expression as input collection to iterate over the tokens only:

=applicants.token

Additionally, please have a look at the following issue regarding call activities in parallel flows: Parallel multi-instance call activity cannot collect output · Issue #4860 · camunda/zeebe · GitHub

Best regards,
Philipp